The present invention relates to packaging and, more particularly to tamper-evident packaging of the type which clearly evidences to a potential purchaser of the product whether or not the integrity of the packaging has been breached.
In recent years, illegal tampering with just a few packages of consumer products, especially consumer products intended for ingestion, have caused death, illness, widespread public fear and the costly recall of millions of packages from retailer's shelves. As a result, there have been numerous and diverse attempts to provide packaging which would show positive visual evidence of any attempt to compromise the integrity or otherwise tamper with the containers in which such products as over the counter drugs, pharmaceuticals, foods or the like are typically packaged. However, none of the commonly used tamper-evident packaging techniques involving folding carton packages have proven to be entirely satisfactory in use. The gluing or sealing of carton ends together has not hampered a skilled and determined tamperer from, for example, using a sharp blade to cut through the carton sealing adhesive, adulterating the contents of the inner package, and then regluing the carton ends without leaving any telltale indication that the integrity of the packaging has been compromised. The use of heat-sealed or shrink-type carton overwrap has not deterred tamperers as the overwrap material is generally available so that the tamperer can easily remove the overwrap from the carton, adulterate the contents of the carton, and apply look-alike overwrap to the carton without leaving any indication that the carton integrity has been compromised. A reliable tamper-evident packaging system must ensure that the tampering causes a permanent change to an essential element of the packaging which is visually evident.
Various patents have been directed to tamper-evident packaging, switch-proof labels and the like.
U.S. Pat. No. 4,097,236 discloses a tamper-evident system which relies on the principle that a ruptured heat-seal exhibits a different color than an unruptured heat seal.
U.S. Pat. No. 4,246,307 discloses a laminated sticker card, the laminate including a printed inner layer which adheres to a substrate and an outer layer. Portions of the printed inner layer adjacent the substrate are preferentially adhered at certain locations to the substrate and at other locations to the outer layer of the laminate, so that an attempt to remove the laminate from the substrate results in tearing of the printed inner layer at the preferentially adhered locations.
U.S. Pat. Nos. 1,003,443 and 4,082,873 disclose switch-proof labels which are intended to prevent labels from being removed from one container and applied to another by causing the tampering to destroy the visual integrity of the labels.
However each of these patented systems requires that the user be alert to the special circumstances which indicate tampering. In other words, the systems fail to provide an unequivocal message which even the first time user of the product will recognize as an intended communication, let alone a warning of tampering.
Accordingly, it is an object of the present invention to provide tamper-evident packaging wherein the tampering is evidenced by the appearance of a desired graphic or verbal communication on the outer surface of the container.
Another object is to provide tamper-evident packaging in which removal of a carton overwrap causes clear and unequivocal notice of tampering to appear on the carton surface, so that such notice will remain on the carton surface even if new overwrap is applied thereto or other steps are taken to attempt to hide the evidence of tampering.
A further object is to provide such tamper-evident packaging at only a minimal cost over regular packaging.
It is also an object to provide a method of manufacturing such tamper-evident packaging and an intermediate useful in such manufacture.